Question: If $x \circledcirc y = 4x-y$ and $x \bigtriangledown y = 2x-4$, find $4 \circledcirc (5 \bigtriangledown -2)$.
First, find $5 \bigtriangledown -2$ $ 5 \bigtriangledown -2 = (2)(5)-4$ $ \hphantom{5 \bigtriangledown -2} = 6$ Now, find $4 \circledcirc 6$ $ 4 \circledcirc 6 = (4)(4)-6$ $ \hphantom{4 \circledcirc 6} = 10$.